HIV-positive bisexual men in care in the United States are more likely to have unprotected (condom-free) anal or vaginal sex than heterosexual men with HIV, according to results of a 2890-man CDC analysis [1]. Bisexuals differed from both straight and gay men with HIV in several demographic variables.

Many HIV-positive US men have sex with both men and women and so may act as a bridge population between gays and heterosexuals. But little research has compared demographic or risk behaviors of bisexual HIV-positive US men with those variables in gay or straight HIV-positive men. Learning more about HIV-positive bisexual men is critical, CDC investigators noted, because they may not be reached by prevention programs aimed at gays or heterosexuals.

A CDC team tried to fill in some of the knowledge gaps by comparing self-identified bisexual, gay, and heterosexual men in the Medical Monitoring Project, a national sample of HIV-positive adults in care. At annual visits, the Medical Monitoring Project gathers behavioral data on HIV-positive adults receiving medical care in 23 cities, states, and territories across the United States. The researchers selected sites to yield nationally representative estimates of characteristics of people in care between January and April 2009. They classified men as sexually active if they had any oral, vaginal, or anal sex in the past 12 months. The researchers defined unprotected discordant sex as vaginal or anal sex without a condom with a partner of negative or unknown HIV status in the past 12 months.

The analysis included 291 bisexual men, 1599 gay men, and 1000 heterosexual men. Proportions of Hispanic men did not differ significantly between bisexual and gay men or between bisexual and straight men. The bisexual group included a significantly lower proportion of whites than the gay group (31% versus 59%, P < 0.0001) and a significantly higher proportion of whites than the heterosexual group (31% versus 17%, P = 0.0005). A significantly higher proportion of bisexuals than gays were black (43% versus 18%, P < 0.0001) and a significantly lower proportion of bisexuals than heterosexuals were black (43% versus 57%, P = 0.0005).

Bisexual men had significantly more education than heterosexual men and significantly less education than gay men (P < 0.0001 for both comparisons, see Table 1 in poster linked below for details). While 41% of bisexual men lived at or below the poverty level, 23% of gay men and 58% of straight men lived below the poverty cutoff (P < 0.0001 for both comparisons). About one quarter of men in all three groups had a lapse in healthcare coverage in the past 12 months.
Bisexual men had significantly more sex partners than straight men (average 3.1 versus 1.5, P < 0.0001) but significantly fewer than gay men (average 5.3, P < 0.0001). Similarly, rates of sex practices were significantly higher in bisexual men than heterosexual men, but significantly lower in bisexual men than straight men for (1) any oral, anal, or vaginal sex, (2) any unprotected anal or vaginal sex, and (3) any unprotected HIV-discordant anal or vaginal sex (see Table 2 in poster linked below).

A logistic regression model that accounted for demographic factors associated with sexual behavior (race, age, education, poverty, health care coverage) determined that heterosexual men were 30% less likely to have unprotected anal or vaginal sex than bisexual men (adjusted prevalence ratio 0.7, 95% confidence interval [CI] 0.5 to 0.8, P = 0.001). Bisexual and gay men did not differ significantly in rates of unprotected anal or vaginal sex. Bisexual men did not differ from either of the other two groups in rates of unprotected anal or vaginal sex with an HIV-negative or status-unknown partner.

The CDC team concluded that this first nationally representative survey of sexual behavior in HIV-positive bisexual men in care found numerous demographic differences and one sex behavior difference between them and heterosexual men or gay men.

"Prevention interventions for bisexual men need to be appropriately tailored" to them, the researchers urged, since "evidence suggests they are less likely to be reached by programs targeting gay or heterosexual men."

"Demographic characteristics of bisexual men significantly different from gay and heterosexual men. Bisexual men are:

More likely to be black, less educated and poor than gay men and more likely to be white, younger, more educated, and above the poverty level than heterosexual men.

Sexual risk behaviors of bisexual men significantly different from gay and heterosexual men. Compared to bisexual men, heterosexual men are independently less likely to report unprotected sex, but do not differ from gay men in unprotected sexual behavior.

This is the first nationally representative survey measuring sexual risk behaviors among HIV- infected bisexual men receiving care.

Prevention interventions for bisexual men need to be appropriately tailored as evidence suggests they are less likely to be reached by programs targeting gay or heterosexual men.

Establishing effective HIV/AIDS prevention programs for behaviorally bisexual men is an important component in reducing the sexual transmission of HIV to both men and women."